Mr Russell wrote:
we're hoping that whatever it is behind the plaster isn't diamond.
I hate to disagree with my husband on this, but I’d forego putting my coat hooks up if I could have walls made of diamond.
But yes, we’ve tried masonry bits on a hammer action drill, and it’s going nowhere. Both drill and the bits it came with are as cheap as it comes, though. Worked fine in the flat, but just not touching these walls beneath the plaster.